1. Technical Field
The present disclosure relates to a printing apparatus which prints an image on a printing medium using a print head including printing elements which eject ink and a printing method.
2. Description of the Related Art
Printing apparatuses form an image by ejecting ink from a plurality of nozzles disposed in a print head. The ink is formed by color material, organic solvent, water, and the like, and a component ratio of the water is particularly high. The water easily evaporates from ejection ports (nozzles) of the print head; and therefore, if ink ejection is not performed for a certain period of time, the color material and the organic solvent of the ink in portions in the vicinity of the ejection ports are condensed. Such condensation of ink prevents the ink from being normally ejected from the ejection ports. For example, the condensation of ink causes deterioration of landing accuracy of ink droplets on a printing medium and miniaturization of ink droplets.
To suppress such disadvantages, preliminary ejection is generally performed before scanning is performed using a print head so that ink condensation is cleared. However, if a blank region (non-image region) having a certain size or larger than the certain size is detected during scanning, the ink condensation progresses in the vicinity of ejection ports during scanning of the blank region; and accordingly, there arises a problem in that ink is not normally ejected at an ejection timing after the blank region is scanned.
To address the problem, Japanese Patent Laid-Open No. 2008-55855 discloses as follows: Change from a region which does not include an image having a certain size or larger than the certain size to a region which includes an image having the certain size or larger than the certain size in a printed image is detected. Thereafter, power for driving a print head for the region which includes the image and which positions after the region which does not include the image in a scanning direction is increased so that the increased power is larger than a regular power. The change from the non-image region to the image-including region is realized by dividing an image region into unit regions corresponding to a plurality of nozzles and counting the number of print dots in the individual unit regions. Japanese Patent Laid-Open No. 2008-55855 discloses determinations of non-image regions and image-including regions by comparing a count value with a predetermined threshold value and change of power at a time when a certain number or more of non-image regions are consecutively detected. By this method, even when ink is condensed in the ejection ports, a sufficient speed of ejection of ink droplets may be maintained, and accordingly, the image degradation described above may be suppressed.